1. Field of the Invention
This invention relates to image partitioning methods and devices, such as computers, on which such methods may be implemented. More particularly, the invention relates to the partitioning of a set of overlapping images to improve downloading and processing efficiency. Overlapping images are partitioned so that when the image data is transmitted (i.e., downloaded) only the visible portions of the images are downloaded. Invisible image portions are not transmitted to conserve bandwidth.
2. Description of the Related Art
Various online utilities exist that let a user create and edit graphics such as business cards and greeting cards over the internet with a standard web browser. Many of these utilities allow the user to add one or more images to the greeting or business card. The user may move the images around, resize them, rotate them, etc.
During the manipulation process, the user is typically dealing only with thumbnail sized images. This minimizes the demands on the client machine. It also minimizes the download time. Downloading of the full size image can be delayed until the user is ready to print. This way, if the user changes his mind about which image he wants to use, no time is wasted downloading a full size image.
In some cases, the user may wish to incorporate in the graphics document multiple images, some of which partially overlap. In any region of overlap only the corresponding portion of the topmost image is visible; the corresponding portions of the images further down in the stack are occluded. Under the current state of the art, when the user wants to download the images, all of the image data is downloaded, even data of image portions that will not be visible. This is time consuming and unnecessary.
It is an object of the present invention to overcome the aforementioned problems and disadvantages of conventional processing of overlapping images.
Another object of this invention is to provide a system for partitioning a set of overlapping images to improve transmitting and processing efficiency.
A further object of this invention is to provide a system for partitioning a set of overlapping images such that only the visible portions of the images are transmitted.
Still another object of this invention is to provide a system for partitioning a set of overlapping images that are in compressed domain and transmitting only the compressed data from the partitioned area.
According to one aspect of this invention, a method is provided for partitioning a group of images including at least a first, bottom-most image and a second image in front of, and partially overlapping, the first image. The method comprises partitioning a non-overlapped portion of the first image into at least two sections based on the position of the second image to form a first set of image elements; and transmitting only the first set of image elements.
If necessary, a non-overlapped portion of each partially overlapped image element in the first set of image elements is preferably further partitioned in a second partitioning stage into at least two sections based on the position a third image in the group of images that partially overlaps the first set of image elements. This second stage of partitioning results in the formation of a second set of image elements. In this case, only the first and second sets of image elements are transmitted.
In another aspect of the invention a method is provided for partitioning a group of images, at least some of which partially overlap, the group of images including a first, bottom-most image and a last, top-most image. The method comprises partitioning a non-overlapped portion of the first image into a plurality of rectangles based on the position of a second image in front of, and partially overlapping, the first image to form a first set of rectangles; iteratively forming new sets of rectangles by partitioning a current set of rectangles based on a next image in the group of images until a final set of rectangles is formed based on the position of the top-most image; and transmitting only the final set of rectangles. Preferably, the first set of rectangles includes the second image and each additional set of rectangles includes the image on which the partitioning for that additional set is based.
Preferably, the first set of image elements includes the second image, and the second set of image elements includes the third image.
Also, preferably, each section and image element is in the shape of a rectangle.
Also, preferably, the partitioning is done in compressed or partially compressed domain.
According to another aspect of the invention, an apparatus is provided for partitioning a group of images in accordance with the above-described method(s). The apparatus, which may be a digital computer, other processor-controlled device, or equivalent.
In yet another aspect of the invention, the above-described method(s) may be embodied in a program of instructions which is stored on a medium readable by a digital computer or other processor-controlled device. Alternatively, the method(s) may be implemented using hardware or a combination of software and hardware.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.